A flow battery is a form of rechargeable battery in which electrolyte containing one or more dissolved electroactive species flows through an electrochemical cell that converts chemical energy directly to electricity. The electrolyte is stored externally, generally in tanks, and is pumped through the cell (or cells) of the reactor. Control of flow batteries requires knowledge of the flow rate and State of Charge (SOC). Together they determine the concentration and availability of reactants at the electrodes and the current that can be drawn from the cell for the best efficiency and within safe limits. The SOC is also used to determine how much energy the battery can store or deliver. This can be used to plan the usage of the battery in a device or within a power supply system. It may also determine the power that the battery can produce.
Using flow sensors is problematic since flow sensors are often expensive, inaccurate, and/or have a short life within the flow battery environment. Obtaining SOC frequently requires additional sensors and monitoring equipment. Increased amount of sensors and equipment increases the cost of the system.
A need exists for a flow battery system which can provide flow determination without the need for using a dedicated flow sensor. A further need exists for a flow battery system which can easily provide SOC determination without the need for additional equipment.